The present invention relates generally to the field of semiconductor technology, and more particularly to semiconductor structures controlling overlap between gate and source/drain contacts in vertical gate-all-around field effect transistors.
Semiconductor device scaling to smaller feature sizes for the last four decades, is facing significant challenges, such as increases in power consumption as increasing OFF-state leakage and non-scalability of the operating voltage, in pursuit of faster device performance. Traditional semiconductor design techniques, processes and materials become ineffective as physical dimensions shrink down to the nanometer regime. The use of gate-all-around metal-oxide semiconductor field effect transistors (MOSFETs) with small area of cross-section gives rise to be better electrostatic control of the channel and thus, leads to lower OFF-state leakage current.
In response to the challenges creating electron barriers in the nanometer regime, a new type of field-effect transistor (FET) for low energy electronics has been developed. A tunnel field-effect transistor (TFET) operates or switches by modulating quantum tunneling through a barrier instead of modulating thermionic emission over a barrier as done in traditional MOSFET technology. Similar in structure to a MOSFET except that the source and drain contacts are doped with the opposite type doping materials, a TFET commonly includes an “intrinsic” layer forming a p-type, intrinsic, n-type (P-I-N) junction in which the electrostatic potential in the intrinsic region is controlled by a gate terminal.
MOSFETs can be either n-channel MOSFETs (NFETs) or p-channel MOSFETs (PFETs). In NFETs, the source contact and the drain contact are doped with n-type doping material. In PFETs, the source contact and the drain contact are doped with p-type doping material. Similarly, TFETs can be either n-channel TFETs (N-TFETs) or p-channel TFETs (P-TFETs). In N-TFETs, the source contact is doped with p-type doping material and the drain contact is doped with n-type doping material. In P-TFETs, the source contact is doped with n-type doping material and the drain contact is doped with p-type doping material.